/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/util/DateParser.java,v 1.11 2004/11/06 19:15:42 mbecke Exp $
 * $Revision: 480424 $
 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.Locale;
import java.util.TimeZone;

/**
 * A utility class for parsing HTTP dates as used in cookies and other headers.
 * This class handles dates as defined by RFC 2616 section 3.3.1 as well as some
 * other common non-standard formats.
 * 
 * @author Christopher Brown
 * @author Michael Becke
 * 
 * @deprecated Use {@link org.apache.commons.httpclient.util.DateUtil}
 */
public class DateParser {

	/**
	 * Date format pattern used to parse HTTP date headers in RFC 1123 format.
	 */
	public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";

	/**
	 * Date format pattern used to parse HTTP date headers in RFC 1036 format.
	 */
	public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";

	/**
	 * Date format pattern used to parse HTTP date headers in ANSI C
	 * <code>asctime()</code> format.
	 */
	public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";

	private static final Collection DEFAULT_PATTERNS = Arrays
			.asList(new String[] { PATTERN_ASCTIME, PATTERN_RFC1036,
					PATTERN_RFC1123 });

	/**
	 * Parses a date value. The formats used for parsing the date value are
	 * retrieved from the default http params.
	 * 
	 * @param dateValue
	 *            the date value to parse
	 * 
	 * @return the parsed date
	 * 
	 * @throws DateParseException
	 *             if the value could not be parsed using any of the supported
	 *             date formats
	 */
	public static Date parseDate(String dateValue) throws DateParseException {
		return parseDate(dateValue, null);
	}

	/**
	 * Parses the date value using the given date formats.
	 * 
	 * @param dateValue
	 *            the date value to parse
	 * @param dateFormats
	 *            the date formats to use
	 * 
	 * @return the parsed date
	 * 
	 * @throws DateParseException
	 *             if none of the dataFormats could parse the dateValue
	 */
	public static Date parseDate(String dateValue, Collection dateFormats)
			throws DateParseException {

		if (dateValue == null) {
			throw new IllegalArgumentException("dateValue is null");
		}
		if (dateFormats == null) {
			dateFormats = DEFAULT_PATTERNS;
		}
		// trim single quotes around date if present
		// see issue #5279
		if (dateValue.length() > 1 && dateValue.startsWith("'")
				&& dateValue.endsWith("'")) {
			dateValue = dateValue.substring(1, dateValue.length() - 1);
		}

		SimpleDateFormat dateParser = null;
		Iterator formatIter = dateFormats.iterator();

		while (formatIter.hasNext()) {
			String format = (String) formatIter.next();
			if (dateParser == null) {
				dateParser = new SimpleDateFormat(format, Locale.US);
				dateParser.setTimeZone(TimeZone.getTimeZone("GMT"));
			} else {
				dateParser.applyPattern(format);
			}
			try {
				return dateParser.parse(dateValue);
			} catch (ParseException pe) {
				// ignore this exception, we will try the next format
			}
		}

		// we were unable to parse the date
		throw new DateParseException("Unable to parse the date " + dateValue);
	}

	/** This class should not be instantiated. */
	private DateParser() {
	}

}
